Ok.

If you can let me know what's involved in "sending it in", I can do so.

In the time since I originally posted, before I read your reply, I decided to check the condition of the diaphragm. It looked to be in good condition, so I cleaned it off and put it back together. Now it doesn't want to run at all. It looks like it's not drawing fuel any more, at least not past the regulator. It's pressurizing the tank when I flip it over, and fuel is getting from the tank to the engine, but not from the front of the engine to the needle valve.

At this point, if you say that there is a modification that corrects this [running lean] problem, then that sounds great to me. I love the engine when it runs, but I haven't ever been able to keep it running properly for any period of time.

Thanks again,
-Wade